Introduction

East Coast fever (theileriosis) is a disease of cattle

Cattle

Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...

, sheep and goats caused by the protozoan parasite Theileria parva

Theileria parva

Theileria parva is a parasitic protozoan, named in honour of Arnold Theiler, that causes East Coast fever in cattle, a costly disease in Africa. The main vector for T. parva is the tick Rhipicephalus appendiculatus...

. The term excludes diseases caused by other Theileria

Theileria

Theileria is a genus of parasitic protozoan that belongs to the phylum Apicomplexa and is closely related to Plasmodium. Two Theileria species, T. annulata and T. parva, are important cattle parasites. T. annulata causes tropical theileriosis and T. parva causes East Coast fever. Theileria are...

, such as tropical theileriosis

Tropical theileriosis

Tropical theileriosis or Mediterranean theileriosis is a theileriosis of cattle from the Mediterranean and Middle East area, from Morocco to Western parts of India and China....

 (also known as Mediterranean theileriosis), caused by T. annulata, and human theileriosis

Theileriosis

* East coast fever * Tropical theileriosis * Corridor disease -External links:*...

, caused by T. microti

Theileria microti

Theileria microti is a parasitic blood-borne piroplasm transmitted by deer ticks. It was previously in the taxonomic genus Babesia, as Babesia microti, until ribosomal RNA comparisons placed it in the sister genus Theileria. T...

.

East Coast fever is among the most important livestock diseases in Africa, causing an annual loss of 1.1 million cattle and $168 million, as of 1992. It is found in Sudan

Sudan

Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...

, South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, the Democratic Republic of Congo, Swaziland, Zimbabwe, Zambia, Tanzania, Kenya, and Uganda. The primary vector for T. parva is Rhipicephalus appendiculatus.

T. parva was first described in 1902 in Zimbabwe, but was misdiagnosed as redwater

Babesiosis

Babesiosis is a malaria-like parasitic disease caused by infection with Babesia, a genus of protozoal piroplasms. After trypanosomes, Babesia are thought to be the second most common blood parasites of mammals and they can have a major impact on health of domestic animals in areas without severe...

 (a disease caused by Babesia bigemina).

Theileria are the only eukaryotic organisms known to transform lymphocytes. The intermediate hosts for T. parva are cattle. The definitive hosts are the ticks. Native cattle are often resistant to the parasite. This is not to say they do not suffer from the parasite; they do. They are hosts to the parasite, but do not suffer as severely as foreign cattle.

Clinical signs and diagnosis

Mortality can be up to 100%, with death occurring around 18–30 days after the initial attachment of infected ticks. This is because the incubation required is around 10–25 days, and the parasite spreads quickly and is rather aggressive.

Clinical signs for diagnosis include but are not limited to fever and enlarged lymph nodes near the tick bite(s). Smears and stains can also be done to check for the parasite. Schizonts (aka meronts, or segmentors) can be found in infected lymphocytes. Pathology includes but is not limited to anorexia

Anorexia (symptom)

Anorexia is the decreased sensation of appetite...

, dyspnea

Dyspnea

Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...

, corneal opacity, nasal discharge, frothy nasal discharge, diarrhea, pulmonary edema

Pulmonary edema

Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...

, leukopenia

Leukopenia

Leukopenia is a decrease in the number of white blood cells found in the blood, which places individuals at increased risk of infection....

, and anemia

Anemia

Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...

. After this, endemic cattle that are given medication sometimes recover to varying degrees, or death follows due to blocked capillaries and parasites infecting the central nervous system

Central nervous system

The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

. Cattle that are endemic

Endemic (epidemiology)

In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. For example, chickenpox is endemic in the UK, but malaria is not...

 and manage to survive tend to be carriers.

A form of East Coast Fever called Corridor Disease is observed when the organism is transmitted from the African Buffalo

African Buffalo

The African buffalo, affalo, nyati, Mbogo or Cape buffalo is a large African bovine. It is not closely related to the slightly larger wild Asian water buffalo, but its ancestry remains unclear...

 to cattle.

Another form called January Disease only occurs over the Winter months in Zimbabwe due to the tick lifecycle.

For diagnosis, post-mortem findings are characteristic and mainly include damage to the lymphoid and respiratory systems.

Treatment and control

One study using the medicinal plant Peganum harmala showed it to have a lifesaving effect on cattle infected with East Coast Fever.

The classical treatment with tetracyclines (1970–1990) can not provide efficiency more than 50 %.

Since the early 1990s

1990s

File:1990s decade montage.png|From left, clockwise: The Hubble Space Telescope floats in space after it was taken up in 1990; American F-16s and F-15s fly over burning oil fields and the USA Lexie in Operation Desert Storm, also known as the 1991 Gulf War; The signing of the Oslo Accords on...

, buparvaquone

Buparvaquone

Buparvaquone is a hydroxynaphthoquinone antiprotozoal drug related to parvaquone and atovaquone. It is a promising compound for the therapy and prophylaxis of all forms of theileriosis. Buparvaquone has been shown to have anti-leishmanial activity in vitro...

is used in bovine theileriosis with remarquable results (90 to 98 % recovery).

Other than the Buparvaquones, another chemotherapeutic option are the Parvaquones e.g. Clexon. Halofuginone Lactate has also been shown to have an 80.5% efficacy against Theirelia parva parva infections.

In May 2010, it was reported that a vaccine to protect cattle against East Coast fever had been approved and registered by the governments of Kenya, Malawi and Tanzania. This consists of cryopreserved sporozoites from crushed ticks but is expensive and can cause disease.

Control of the disease also relies on tick control and the development of resistant ticks to the disease.